I am having two boards(1.5Feet x 1Feet each) which are connected in a backplane. I2C master is in BOARD1 and the slave(Temperature Sensor) in BOARD2. In 100KHz mode, I am able to read the slave properly but when I move to 400KHz mode I am not gettign any response from slave.
Please find the attached diagram for the I2C diagram, there are some MUX and SWITCHES are connected on the I2C lines. I have shown only SCL in the picture but SDA is also the same connection.
In the above case there are 3 pull up resistors on both SCL and SDA line. Can anyone tell us how to find the right pull up value for all three resistors.
And one more thing is BOARD1 and BOARD2 has their own 3.3V supply generated on board. I have also written the input capacitance of each devices in the picture.